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Should WCAG 2.1 require conformance on MAC OS?

The first question the title of this blog raises is "Doesn't WCAG 2.0 apply to both MAC OS and Windows OS"? The answer is "yes and no".

  • Yes: because an author "could" declare that for the Accessibility Support Requirements of WCAG 2, they are relying on MAC OS.
  • No: because authors are only required to declare conformance for one stack. And in all reality, its much easier to conform on the Windows OS than MAC OS.

So, the next question is: Should we require WCAG 2.1, which will be released next year, to require conformance on two separate operating systems?

There was a thread which sprung up on Twitter regarding WCAG conformance requirements, @stevefaulkner said that on the Open Web we should require sites to work on both Windows or Mac platforms. Others commented similarly.


WCAG presently requires at least one accessibility supported way to meet each Success Criterion, and they can't switch back and forth... in other words all SCs have to be met on the same stack.

An author could rely on MacOS with VoiceOver, etc to claim conformance, but in reality I've never seen that. However, its becoming more realistic.

This proposal would require at least one accessibility supported way to meet all SCs on at least two OS.


  • It would effectively put MacOS in the requirements.
  • It would give people with disabilities more choices
  • Would motivate stakeholders in the Mac world to take accessibility more seriously.
  • [feel free to add more in the comments, I'll add them here]


  • Would increase QA and testing significantly
  • Increase workload on developers to provide work around solutions for two separate stacks. At least on Windows if JAWS doesn't work on something NVDA might. On MACOS there's only VoiceOver, so when there is a bug, there is no accessibility supported way of meeting the SC, which would...
  • Put sites at risk of non-conformance if there are bugs in one or the other systems. So it would be a significant expansion of the requirements of WCAG.
  • Windows is still ahead of MAC on most metrics for accessibility, and most blind individuals who are serious about working and employment still rely on Windows. If they have a Mac, its usually their second machine. (conversely for Mobile, iOS is the clear leader)
  • Could inhibit uptake of WCAG 2.1 in legislation for reasons above.
  • [feel free to add more in the comments, I'll add them here]

The discussion was passionate enough that I think this needs to be explored seriously by the group and a formal decision process be documented for WCAG 2.1 rather than relying on the WCAG 2.0 rationale which was that a the time Windows was really the only OS that could reliably provide a way to meet the Success Criteria.

What are your thought? Is this realistic to require of businesses, and government?

Feel free to comment on Twitter @davidmacd

Author information:

David MacDonald is a veteran WCAG member, co-editor of Using WAI ARIA in HTML5 and HTML5 Accessibility Task Force Member. Opinions are my own.


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